Approximately 4,000 adolescents and young adults, ages 15-24, commit suicide each year. Moreover, an even greater number of youth make non-lethal suicide attempts (estimated at 100-200 suicide attempts for each completed suicide), often preceded by severe suicidal ideation (SI). Many risk factors for suicide have been identified in previous research. Child maltreatment, particularly child sexual and physical abuse, is robustly associated with SI in adolescence. Despite the consistency of this association, we know surprisingly little about mechanisms that may help explain why some maltreated individuals go on to contemplate suicide while others do not. Increased emotional reactivity and impaired regulation are associated with increased risk of SI. Emerging research suggests that child maltreatment influences emotional reactivity and regulation. Thus, one potential mechanism may be through neural systems involved in emotion regulation. The primary aim of this proposal is to examine the effects of child maltreatment on the neural systems involved in emotion regulation and associated SI. Specifically, this proposal will examine the effects of child maltreatment on amygdala activation (reactivity) when participants view negative (vs neutral) stimuli. Similarly, this proposal will examine ventral medial prefrontal cortex (vmPFC) activation during trials when participants are asked to down-regulate their emotional response (regulation) (Hypothesis 1). Next, this study will examine the associations between amygdala reactivity and vmPFC activation and SI (Hypothesis 2). Finally, this study will examine these neural systems as potential mediators of the association between child adversity and SI (Hypothesis 3). Participants will be drawn from a larger, primary R01 grant and employs multiple methods to answer study questions. These include neuroimaging, self- and parent-report, clinical interview, and psychophysiological measures. The sample size will include 100 youth, 50 with a history of child maltreatment and 50 matched controls. Exploratory analyses will examine whether or not these neural systems are specific to SI, or may also be associated with other forms of self-injury, including nonsuicidal self-injury and suicide attempts. The results of this study will contribute to developmental models of adolescent emotion regulation, and also will yield information to improve the identification of SI risk among youth. Training as part of this award includes developmental cognitive neuroscience (including neuroimaging), developmental psychopathology, and advanced statistical approaches to developmental data.